This invention relates to optical devices, and more particularly to optical waveguide devices.
In the integrated circuit industry, there is a continuing effort to increase device speed and increase device densities. Optical systems are a technology that promise to increase the speed and current density of the circuits. Optical devices, such as optical modulators are used in these optical systems. Such optical modulators can be used to perform a variety of functions in integrated circuits such as signal transmission and attenuation. Optical modulators typically require different devices to phase modulate or amplitude modulate light.
Optical devices that perform different functions are typically formed and shaped differently in order to perform the different functions. As such, each type of optical device, and each size of the same optical device type, has to be manufactured distinctly. Therefore, the production of precision optical devices is expensive. Additionally, optical devices are susceptible to changes in temperature, contact, pressure, humidity, etc. As such, the optical devices are typically contained in packaging that maintains the conditions under which the optical devices are operating. Providing such packaging is extremely expensive. Even if such packaging is provided, passive optical devices may be exposed to slight condition changes. As such, the passive optical devices perform differently under the different conditions. The modulators will modulate the light a different amount. If the characteristics of a passive optical device is altered outside of very close tolerances, then the optical device will not adequately perform its function. In other words, there is no adjustability for passive optical devices such as modulators.
It would therefore be desirable to provide an optical modulator that can both phase modulate and amplitude modulate, or a combination of the two, using the same device. Additionally, it would be desired to provide an optical device whose operation can be adjusted either to control the amount of modulation, or to compensate for changed parameters.
A self-aligned optical modulator that modulates an input optical signal in order to generate a modulated output optical signal includes an optical modulator device including a waveguide, a first modulating electrode, a second modulating electrode, and a two-dimensional electron (hole) gas (2DEG) proximate the first modulating electrode, the waveguide includes an input port wherein the input optical signal is introduced into the waveguide, an output port wherein the modulated output optical signal exits the waveguide, and a region of modulating propagation constant disposed along a first length of the waveguide and between the input port and the output port, wherein the input optical signal is guided by total internal reflection in the waveguide, and the waveguide is formed at least in part from an active semiconductor. The first modulating electrode is positioned proximate a first surface of the region of modulating propagation constant and electrically separated from an active semiconductor. The second modulating electrode is in electrical contact with the active semiconductor and disposed on a first side of the region of modulating propagation. The two-dimensional electron (hole) gas (2DEG) proximate the first modulating voltage is applied between the first modulating electrode and the second modulating electrode, wherein modulation of the voltage by the optical modulation device causes a corresponding modulation of the free carrier distribution which, in turn, causes corresponding modulation of a propagation constant level in the region of modulating propagation constant. A first deflector deflects light in a first lateral direction within the waveguide, and a second deflector configured to deflect light in a second lateral direction towards the waveguide wherein the deflection of the first deflector or the second deflector acts to direct light approaching the region of modulating propagation constant towards the region of modulating propagation constant.